program crash at zlog_thread_del()

[yinhanng]

thanks for this project, but i find one bug when use zlogwin at multithread env, zlog_thread_del crashs, accept zlog_thread_t **, which is diffrent to the original zlog project zlog_thread_t *, i change this logic to original, the crash has gone,
as next
void zlog_thread_del(zlog_thread_t ** a_thread); ===>void zlog_thread_del(zlog_thread_t * a_thread);
i don't if my change to code is correct